The present invention relates to a computer system which operates upon downloading programs and data from a server (server computer) via a network, and a file resources switching method applied to the computer system.
This application is based on Japanese Patent Application No. 10-047287 filed on Feb. 27, 1998, the content of which is incorporated herein by reference.
In recent years, new computer architectures called Network Computers have been developed instead of personal computers.
The network computer is designed to be used based on connection to a network. All programs and data necessary for data processing are downloaded from a server via a network. Therefore, each network computer operating as a client computer need not have programs and data, and can flexibly cope with, e.g., updating of an Operating System (OS) and application programs. As a result, total costs of ownership can be drastically reduced.
However, as described above, the network computer is designed to be used based on connection to a network, and is not usually designed to be used in a mobile environment where the computer is disconnected to the network. It is, therefore, necessary to develop a new network computer which can perform the same operations as in the online state in which the computer is connected to the network even if the computer operates in the offline state in which the computer is not connected to the network.
In order to realize a network computer which can be used in a mobile environment, it is necessary to provide a local storage, in which copies of resources on the server necessary for operating in the offline state are stored, in the network computer and to enable the network computer to operate using the local storage device.
In this case, however, the file system to be accessed differs between the online state and the offline state. As a result, it is necessary to clearly distinguish the network file system of the server from the local file system of the local storage. For this reason the user or the application program of the network computer must explicitly designate a file system to be accessed while being aware of the state of the connection of the network computer to a network. Furthermore, the network file system of the server cannot be accessed in the same procedures as those of the local file system of the local storage.
Note that "file system" means "hierarchy structured file set" and "file system" will be used based on this meaning hereinafter.